Friehling, who helped run a small accounting firm in Rockland County, is accused of helping Madoff get away with the $50 billion fraud for so long by allegedly filing false audit reports about Madoff's investments without performing any review.

In addition to securities fraud, Friehling is also charged with investment adviser fraud, making false filings to the Securities and Exchange Commission and obstructing the IRS.

Friehling becomes the second known Madoff associate to cooperate in the investigation. Madoff's right hand man Frank DiPascali pleaded guilty and is hoping for a reduced sentence by helping the FBI track others involved.

DiPascali is behind bars as prosecutors try to convince a judge to let the convicted co-conspirator out on bail so he can more easily assist the investigation.